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<table width="100%" summary="page for Somerville"><tr><td>Somerville</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Visits to Lake Somerville </h2>

<h3>Description</h3>

<p>a cross-section from 1980
</p>
<p><em>number of observations</em> :  659
</p>
<p><em>observation</em> :  individuals
</p>
<p><em>country</em> :  United States
</p>


<h3>Usage</h3>

<pre>data(Somerville)</pre>


<h3>Format</h3>

<p>A dataframe containing :
</p>

<dl>
<dt>visits</dt><dd><p>annual number of visits to lake Somerville</p>
</dd>
<dt>quality</dt><dd><p>quality ranking score for lake Somerville</p>
</dd>
<dt>ski</dt><dd><p>engaged in water&ndash;skiing at the lake ?</p>
</dd>
<dt>income</dt><dd><p>annual household income</p>
</dd>
<dt>feeSom</dt><dd><p>annual user fee paid at lake Somerville ?</p>
</dd>
<dt>costCon</dt><dd><p>expenditures when visiting lake Conroe</p>
</dd>
<dt>costSom</dt><dd><p>expenditures when visiting lake Somerville</p>
</dd>
<dt>costHoust</dt><dd><p>expenditures when visiting lake Houston</p>
</dd>
</dl>



<h3>Source</h3>

<p>Seller, Christine,  John R.   Stoll and  Jean&ndash;Paul  Chavas (1985) &ldquo;Valuation of empirical measures of welfare change : a comparison of nonmarket techniques&rdquo;, <em>Land Economics</em>, <b>61(2)</b>, may, 156&ndash;175.
</p>
<p>Gurmu, Shiferaw  and  Pravin K.  Trivedi (1996) &ldquo; Excess zeros in count models for recreational trips&rdquo;, <em>Journal of Business and Economics Statistics</em>, <b>14(4)</b>, october, 469&ndash;477.
</p>
<p>Santos Silva, Jao M. C. (2001) &ldquo;A score test for non&ndash;nested hypotheses with applications to discrete data models&rdquo;, <em>Journal of Applied Econometrics</em>, <b>16(5)</b>, 577&ndash;597.
</p>


<h3>References</h3>

<p>Journal of Business Economics and Statistics web site : <a href="http://amstat.tandfonline.com/loi/ubes20">http://amstat.tandfonline.com/loi/ubes20</a>.
Cameron, A.C.  and   Trivedi P.K. (1998) <em>Regression analysis of count data</em>, Cambridge University Press, <a href="http://cameron.econ.ucdavis.edu/racd/racddata.html">http://cameron.econ.ucdavis.edu/racd/racddata.html</a>, chapter 6.
</p>


<h3>See Also</h3>

<p><code>Index.Source</code>, <code>Index.Economics</code>, <code>Index.Econometrics</code>, <code>Index.Observations</code></p>


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